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Use Cases for DC Network Virtualization Overlays

The information below is for an old version of the document.
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This is an older version of an Internet-Draft that was ultimately published as RFC 8151.
Authors Lucy Yong , Mehmet Toy , Aldrin Isaac , Vishwas Manral , Linda Dunbar
Last updated 2013-05-01
Replaces draft-mity-nvo3-use-case
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Network Working Group                                           L. Yong
Internet Draft                                                   Huawei
Category: Informational                                          M. Toy
                                                               A. Isaac
                                                              V. Manral
                                                              L. Dunbar

Expires: November 2013                                  May 1, 2013

             Use Cases for DC Network Virtualization Overlays



   This document describes the DC NVO3 use cases that may be
   potentially deployed in various data centers and apply to different
   applications. An application in a DC may be a combination of some
   use cases described here.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   The list of current Internet-Drafts can be accessed at

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   This Internet-Draft will expire on November, 2013.

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Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document. Please review these documents
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   warranty as described in the Simplified BSD License.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [RFC2119].

Table of Contents

   1. Introduction...................................................3
      1.1. Contributors..............................................4
      1.2. Terminology...............................................4
   2. Basic Virtual Networks in a Data Center........................5
   3. Interconnecting DC Virtual Network and External Networks.......6
      3.1. DC Virtual Network Access via Internet....................6
      3.2. DC VN and Enterprise Sites interconnected via SP WAN......7
   4. DC Applications Using NVO3.....................................8
      4.1. Supporting Multi Technologies and Applications in a DC....9
      4.2. Tenant Network with Multi-Subnets or across multi DCs.....9
      4.3. Virtual Data Center (vDC)................................11
   5. OAM Considerations............................................13
   6. Summary.......................................................13
   7. Security Considerations.......................................14
   8. IANA Considerations...........................................14
   9. Acknowledgements..............................................14
   10. References...................................................14
      10.1. Normative References....................................14
      10.2. Informative References..................................15
   Authors' Addresses...............................................15

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1. Introduction

   Server Virtualization has changed IT industry in terms of efficiency,
   cost, and the speed in providing a new applications and/or services.
   However the problems in today's data center networks hinder the
   support of an elastic cloud service and dynamic virtual tenant
   networks [NVO3PRBM]. The goal of DC Network Virtualization Overlays,
   i.e. NVO3, is to decouple the communication among tenant systems
   from DC physical networks and to allow one physical network
   infrastructure to provide: 1) traffic isolation among tenant virtual
   networks over the same physical network; 2) independent address
   space in each virtual network and address isolation from the
   infrastructure's; 3) Flexible VM placement and move from one server
   to another without any of the physical network limitations. These
   characteristics will help address the issues that hinder true
   virtualization in the data centers [NVO3PRBM].

   Although NVO3 enables a true virtualization environment, the NVO3
   solution has to address the communication between a virtual network
   and a physical network. This is because 1) many DCs that need to
   provide network virtualization are currently running over physical
   networks, the migration will be in steps; 2) a lot of DC
   applications are served to Internet users which run directly on
   physical networks; 3) some applications are CPU bound like Big Data
   analytics and may not need the virtualization capability.

   This document is to describe general NVO3 use cases that apply to
   various data centers. Three types of the use cases described here

   o  A virtual network connects many tenant systems within a Data
      Center and form one L2 or L3 communication domain. A virtual
      network segregates its traffic from others and allows the VMs in
      the network moving from one server to another. The case may be
      used for DC internal applications that constitute the DC East-
      West traffic.

   o  A DC provider offers a secure DC service to an enterprise
      customer and/or Internet users. In these cases, the enterprise
      customer may use a traditional VPN provided by a carrier or an
      IPsec tunnel over Internet connecting to a NVO3 network within a
      provider DC. This is mainly constitutes DC North-South traffic.

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   o  A DC provider may use NVO3 and other network technologies for a
      tenant network, construct different topologies or zones for a
      tenant network, and may design a variety of cloud applications
      that may require the network service appliance, virtual compute,
      storage, and networking. In this case, the NVO3 provides the
      networking functions for the applications.

   The document uses the architecture reference model defined in
   [NVO3FRWK] to describe the use cases.

1.1. Contributors

      Vinay Bannai
      2211 N. First St,
      San Jose, CA 95131
      Phone: +1-408-967-7784

      Ram Krishnan
      Brocade Communications
      San Jose, CA 95134
      Phone: +1-408-406-7890

1.2.  Terminology

   This document uses the terminologies defined in [NVO3FRWK],
   [RFC4364]. Some additional terms used in the document are listed

   CPE: Customer Premise Equipment

   DMZ: Demilitarized Zone

   DNS: Domain Name Service

   NAT: Network Address Translation

   VIRB: Virtual Integrated Routing/Bridging

   Note that a virtual network in this document is a network
   virtualization overlay instance.

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2. Basic Virtual Networks in a Data Center

   A virtual network may exist within a DC. The network enables a
   communication among Tenant Systems (TSs) that are in a Closed User
   Group (CUG). A TS may be a physical server or virtual machine (VM)
   on a server. The network virtual edge (NVE) may co-exist with Tenant
   Systems, i.e. on an end-device, or exist on a different device, e.g.
   a top of rack switch (ToR). A virtual network has a unique virtual
   network identifier (may be local or global unique) for an NVE to
   properly differentiate it from other virtual networks.

   The TSs attached to the same NVE are not necessary in the same CUG,
   i.e. in the same virtual network. The multiple CUGs can be
   constructed in a way so that the policies are enforced when the TSs
   in one CUG communicate with the TSs in other CUGs.  An NVE provides
   the reachbility for Tenant Systems in a CUG, and may also have the
   policies and provide the reachbility for Tenant Systems in different
   CUGs (See section 4.2). Furthermore in a DC operators may construct
   many tenant networks that have no communication at all. In this
   case, each tenant network may use its own address space. Note that
   one tenant network may contain one or more CUGs.

   A Tenant System may also be configured with multiple addresses and
   participate in multiple virtual networks, i.e. use different address
   in different virtual network. For examples, a TS is NAT GW; or a TS
   is a firewall server for multiple CUGs.

   Network Virtualization Overlay in this context means the virtual
   networks over DC infrastructure network via a tunnel, i.e. a tunnel
   between any pair of NVEs. This architecture decouples tenant system
   address schema from the infrastructure address space, which brings a
   great flexibility for VM placement and mobility. This also makes the
   transit nodes in the infrastructure not aware of the existence of
   the virtual networks. One tunnel may carry the traffic belonging to
   different virtual networks; a virtual network identifier is used for
   traffic segregation in a tunnel.

   A virtual network may be an L2 or L3 domain. An NVE may be a member
   of several virtual networks each of which is in L2 or L3. A virtual
   network may carry unicast traffic and/or broadcast/multicast/unknown
   traffic from/to tenant systems. An NVE may use p2p tunnels or a p2mp
   tunnel to transport broadcast or multicast traffic, or may use other
   mechanisms [NVO3MCAST].

  It is worth to mention two distinct cases here. The first is that TS
  and NVE are co-located on a same end device, which means that the
  NVE can be made aware of the TS state at any time via internal API.

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  The second is that TS and NVE are remotely connected, i.e. connected
  via a switched network or point-to-point link. In this case, a
  protocol is necessary for NVE to know TS state.

  One virtual network may have many NVE members each of which many TSs
  may attach to. TS dynamic placement and mobility results in frequent
  changes in the TS and NVE bindings. The TS reachbility update
  mechanism MUST be fast enough to not cause any service interruption.
  The capability of supporting a lot of TSs in a tenant network and a
  lot of tenant networks is critical for NVO3 solution.

   If a virtual network spans across multiple DC sites, one design is
   to allow the corresponding NVO3 instance seamlessly span across
   those sites without DC gateway routers' termination. In this case,
   the tunnel between a pair of NVEs may in turn be tunneled over other
   intermediate tunnels over the Internet or other WANs, or the intra
   DC and inter DC tunnels are stitched together to form an end-to-end
   virtual network across DCs. The latter is described in section 3.2.
   Section 4.2 describes other options.

3. Interconnecting DC Virtual Network and External Networks

   For customers (an enterprise or individuals) who want to utilize the
   DC provider's compute and storage resources to run their
   applications, they need to access their systems hosted in a DC
   through Internet or Service Providers' WANs. A DC provider may
   construct an NVO3 network which all the resources designated for a
   customer connect to and allow the customer to access their systems
   via the network. This, in turn, becomes the case of interconnecting
   a DC NVO3 network and external networks via Internet or WANs. Two
   cases are described here.

3.1. DC Virtual Network Access via Internet

   A user or an enterprise customer connects securely to a DC virtual
   network via Internet. Figure 1 illustrates this case. A virtual
   network is configured on NVE1 and NVE2 and two NVEs are connected
   via an L3 tunnel in the Data Center. A set of tenant systems are
   attached to NVE1 on a server. The NVE2 resides on a DC Gateway
   device. NVE2 terminates the tunnel and uses the VNID on the packet
   to pass the packet to the corresponding VN GW entity on the DC GW. A
   user or customer can access their systems, i.e. TS1 or TSn, in the
   DC via Internet by using IPsec tunnel [RFC4301]. The IPsec tunnel is
   between the VN GW and the user or CPE at enterprise edge location.
   The VN GW provides IPsec functionality such as authentication scheme
   and encryption, as well as the mapping to the right virtual network
   entity on the DC GW. Note that 1) some VN GW functions such as

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   firewall and load balancer may also be performed by locally attached
   network appliance devices; 2) The virtual network in DC may use
   different address space than external users, then VN GW serves the
   NAT function.

         |   TS1 TSn     |
         |    |...|      |
         |  +-+---+-+    |             External User
         |  |  NVE1 |    |               +-----+
         |  +---+---+    |               | PC  |
         +------+--------+               +--+--+
                |                           *
            L3 Tunnel                       *
                |                           *
   DC GW +------+---------+            .--.  .--.
         |  +---+---+     |           (    '*   '.--.
         |  |  NVE2 |     |        .-.'   *          )
         |  +---+---+     |       (    *  Internet    )
         |  +---+---+.    |        ( *               /
         |  | VNGW1 * * * * * * * * '-'          '-'
         |  +-------+ |   | IPsec       \../ \.--/'
         |   +--------+   | Tunnel

           DC Provider Site

             Figure 1 DC Virtual Network Access via Internet

3.2. DC VN and Enterprise Sites interconnected via SP WAN

   An Enterprise company would lease some DC provider compute resources
   to run some applications. For example, the company may run its web
   applications at DC provider sites but run backend applications in
   their own DCs. The Web applications and backend applications need to
   communicate privately. DC provider may construct a NVO3 network to
   connect all VMs running the Enterprise Web applications. The
   enterprise company may buy a p2p private tunnel such as VPWS from a
   SP to interconnect its site and the NVO3 network in provider DC site.
   A protocol is necessary for exchanging the reachability between two
   peering points and the traffic are carried over the tunnel. If an
   enterprise has multiple sites, it may buy multiple p2p tunnels to
   form a mesh interconnection among the sites and DC provider site.
   This requires each site peering with all other sites for route

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   Another way to achieve multi-site interconnection is to use Service
   Provider (SP) VPN services, in which each site only peers with SP PE
   site. A DC Provider and VPN SP may build a NVO3 network (VN) and VPN
   independently. The VN provides the networking for all the related
   TSes within the provider DC. The VPN interconnects several
   enterprise sites, i.e. VPN sites. The DC provider and VPN SP further
   connect the VN and VPN at the DC GW/ASBR and SP PE/ASBR. Several
   options for the interconnection of the VN and VPN are described in
   RFC4364 [RFC4364]. In Option A with VRF-LITE [VRF-LITE], both DC GW
   and SP PE maintain the routing/forwarding table, and perform the
   table lookup in forwarding. In Option B, DC GW and SP PE do not
   maintain the forwarding table, it only maintains the VN and VPN
   identifier mapping, and exchange the identifier on the packet in the
   forwarding process. In option C, DC GW and SP PE use the same
   identifier for VN and VPN, and just perform the tunnel stitching,
   i.e. change the tunnel end points. Each option has pros/cons (see
   RFC4364) and has been deployed in SP networks depending on the
   applications. The BGP protocols may be used in these options for
   route distribution. Note that if the provider DC is the SP Data
   Center, the DC GW and PE in this case may be on one device.

   This configuration allows the enterprise networks communicating to
   the tenant systems attached to the VN in a provider DC without
   interfering with DC provider underlying physical networks and other
   virtual networks in the DC. The enterprise may use its own address
   space on the tenant systems attached to the VN. The DC provider can
   manage the VMs and storage attachment to the VN for the enterprise
   customer. The enterprise customer can determine and run their
   applications on the VMs. See section 4 for more.

   The interesting feature in this use case is that the VN and compute
   resource are managed by the DC provider. The DC operator can place
   them at any location without notifying the enterprise and WAN SP
   because the DC physical network is completely isolated from the
   carrier and enterprise network. Furthermore, the DC operator may
   move the VMs assigned to the enterprise from one sever to another in
   the DC without the enterprise customer awareness, i.e. no impact on
   the enterprise 'live' applications running these resources. Such
   advanced features bring DC providers great benefits in serving these
   kinds of applications but also add some requirements for NVO3

4. DC Applications Using NVO3

   NVO3 brings DC operators the flexibility in designing and deploying
   different applications in an end-to-end virtualization environment,
   where the operators not need worry about the constraints of the

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   physical network configuration in the Data Center. DC provider may
   use NVO3 in various ways and also use it in the conjunction with
   physical networks in DC for many reasons. This section highlights
   some use cases but not limits to.

4.1. Supporting Multi Technologies and Applications in a DC

   Most likely servers deployed in a large data center are rolled in at
   different times and may have different capacities/features. Some
   servers may be virtualized, some may not; some may be equipped with
   virtual switches, some may not. For the ones equipped with
   hypervisor based virtual switches, some may support VxLAN [VXLAN]
   encapsulation, some may support NVGRE encapsulation [NVGRE], and
   some may not support any types of encapsulation. To construct a
   tenant virtual network among these servers and the ToR switches, it
   may construct one virtual network overlay and one virtual network
   w/o overlay, or two virtual networks overlay with different
   implementations. For example, one virtual network overlay uses VxLAN
   encapsulation and another virtual network w/o overlay uses
   traditional VLAN or another virtual network overlay uses NVGRE.

   The gateway device or virtual gateway on a device may be used. The
   gateway participates in to both virtual networks. It performs the
   packet encapsulation/decapsulation and may also perform address
   mapping or translation, and etc.

   A data center may be also constructed with multi-tier zones. Each
   zone has different access permissions and run different applications.
   For example, the three-tier zone design has a front zone (Web tier)
   with Web applications, a mid zone (application tier) with service
   applications such as payment and booking, and a back zone (database
   tier) with Data. External users are only able to communicate with
   the web application in the front zone. In this case, the
   communication between the zones MUST pass through the security
   GW/firewall. The network virtualization may be used in each zone. If
   individual zones use the different implementations, the GW needs to
   support these implementations as well.

4.2. Tenant Network with Multi-Subnets or across multi DCs

   A tenant network may contain multiple subnets. DC operators may
   construct multiple tenant networks. The access policy for inter-
   subnets is often necessary. To benefit the policy management, the
   policies may be placed at some designated gateway devices only. Such
   design requires the inter-subnet traffic MUST be sent to one of the
   gateways first for the policy checking. However this may cause
   traffic hairpin on the gateway in a DC. It is desirable that an NVE

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   can hold some policy and be able to forward inter-subnet traffic
   directly. To reduce NVE burden, the hybrid design may be deployed,
   i.e. an NVE can perform forwarding for the selected inter-subnets
   and the designated GW performs for the rest. For example, each NVE
   performs inter-subnet forwarding for a tenant, and the designated GW
   is used for inter-subnet traffic from/to the different tenant

   A tenant network may span across multiple Data Centers in distance.
   DC operators may want an L2VN within each DC and L3VN between DCs
   for a tenant network. L2 bridging has the simplicity and endpoint
   awareness while L3 routing has advantages in policy based routing,
   aggregation, and scalability. For this configuration, the virtual
   L2/L3 gateway can be implemented on DC GW device. Figure 2
   illustrates this configuration.

   Figure 2 depicts two DC sites. The site A constructs an L2VN with
   NVE1, NVE2, and NVE3. NVE1 and NVE2 reside on the servers where the
   tenant systems are created. NVE3 resides on the DC GW device. The
   site Z has similar configuration with NVE3 and NVE4 on the servers
   and NVE6 on the DC GW. An L3VN is configured between the NVE5 at
   site A and the NVE6 at site Z. An internal Virtual Integrated
   Routing and Bridging (VIRB) is used between L2VNI and L3VNI on NVE5
   and NVE6. The L2VNI is the MAC/NVE mapping table and the L3VNI is
   the IP prefix/NVE mapping table. A packet to the NVE5 from L2VN will
   be decapsulated and converted into an IP packet and then
   encapsulated and sent to the site Z.

   Note that both the L2VNs and L3VN in Figure 2 are encapsulated and
   carried over within DC and across WAN networks, respectively.

   NVE5/DCGW+------------+                  +-----------+NVE6/DCGW
            | +-----+    | '''''''''''''''' |   +-----+ |
            | |L3VNI+----+'    L3VN        '+---+L3VNI| |
            | +--+--+    | '''''''''''''''' |   +--+--+ |
            |    |VIRB   |                  |  VIRB|    |
            | +--+---+   |                  |  +---+--+ |
            | |L2VNIs|   |                  |  |L2VNIs| |
            | +--+---+   |                  |  +---+--+ |
            +----+-------+                  +------+----+
             ''''|''''''''''                 ''''''|'''''''
            '     L2VN      '               '     L2VN     '
      NVE1/S ''/'''''''''\'' NVE2/S    NVE3/S'''/'''''''\'' NVE4/S
        +-----+---+  +----+----+        +------+--+ +----+----+
        | +--+--+ |  | +--+--+ |        | +---+-+ | | +--+--+ |

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        | |L2VNI| |  | |L2VNI| |        | |L2VNI| | | |L2VNI| |
        | ++---++ |  | ++---++ |        | ++---++ | | ++---++ |
        +--+---+--+  +--+---+--+        +--+---+--+ +--+---+--+
           |...|        |...|              |...|       |...|

             Tenant Systems                  Tenant Systems

                DC Site A                    DC Site Z

          Figure 2 Tenant Virtual Network with Bridging/Routing

4.3. Virtual Data Center (vDC)

   Enterprise DC's today may often use several routers, switches, and
   network appliance devices to construct its internal network, DMZ,
   and external network access. A DC Provider may offer a virtual DC
   service to an enterprise customer and run enterprise applications
   such as website/emails as well. Instead of using many hardware
   devices to do it, with the network virtualization overlay
   technology, DC operators may build such vDCs on top of a common
   network infrastructure for many such customers and run network
   service applications per a vDC basis. The net service applications
   such as firewall, DNS, load balancer can be designed per vDC. The
   network virtualization overlay further enables potential for vDC
   mobility when customer moves to different locations because tenant
   systems and net appliances configuration can be completely decouple
   from the infrastructure network.

   Figure 3 below illustrates one scenario. For the simple
   illustration, it only shows the L3VN or L2VN as virtual and overlay
   routers or switches. In this case, DC operators construct several L2
   VNs (L2VNx, L2VNy, L2VNz) in Figure 3 to group the end tenant
   systems together per application basis, create an L3VNa for the
   internal routing. A net device (may be a VM or server) runs
   firewall/gateway applications and connects to the L3VNa and
   Internet. A load Balancer (LB) is used in L2VNx. A VPWS p2p tunnel
   is also built between the gateway and enterprise router. The design
   runs Enterprise Web/Mail/Voice applications at the provider DC site;
   lets the users at Enterprise site to access the applications via the
   VPN tunnel and Internet via a gateway at the Enterprise site; let
   Internet users access the applications via the gateway in the
   provider DC.

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   The Enterprise customer decides which applications are accessed by
   intranet only and which by both intranet and extranet; DC operators
   then design and configure the proper security policy and gateway
   function. Furthermore DC operators may use multi-zones in a vDC for
   the security and/or set different QoS levels for the different
   applications based on customer applications.

   This use case requires the NVO3 solution to provide the DC operator
   an easy way to create a VN and NVEs for any design and to quickly
   assign TSs to a VNI on a NVE they attach to, easily to set up
   virtual topology and place or configure policies on an NVE or VMs
   that run net services, and support VM mobility. Furthermore, DC
   operator needs to view the tenant network topology and know the
   tenant node capability and is able to configure a net service on the
   tenant node. DC provider may further let a tenant to manage the vDC

                         Internet                      ^ Internet
                            ^                        +-+----+
                            |                        |  GW  |
                            |                        +--+---+
                            |                           |
                    +-------+--------+                +-+----+
                    |FireWall/Gateway+--- VPWS/MPLS---+Router|
                    +-------+--------+                +-+--+-+
                            |                           |  |
                         ...+...                        |..|
                  +-----: L3VNa :--------+              LANs
                +-+-+    .......         |
                |LB |        |           |         Enterprise Site
                +-+-+        |           |
               ...+...    ...+...     ...+...
              : L2VNx :  : L2VNy :   : L2VNz :
               .......    .......     .......
                 |..|       |..|        |..|
                 |  |       |  |        |  |
               Web Apps   Mail Apps    VoIP Apps

                        Provider DC Site

    firewall/gateway and Load Balancer (LB) may run on a server or VMs

                Figure 3 Virtual Data Center by Using NVO3

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5. OAM Considerations

   NVO3 brings the ability for a DC provider to segregate tenant
   traffic. A DC provider needs to manage and maintain NVO3 instances.
   Similarly, the tenant needs to be informed about underlying network
   failures impacting tenant applications or the tenant network is able
   to detect both overlay and underlay network failures and builds some
   resiliency mechanisms.

   Various OAM and SOAM tools and procedures are defined in [IEEE
   802.1ag], [ITU-T Y.1731], [RFC4378], [RFC5880], [ITU-T Y.1564] for
   L2 and L3 networks, and for user, including continuity check,
   loopback, link trace, testing, alarms such as AIS/RDI, and on-demand
   and periodic measurements. These procedures may apply to tenant
   overlay networks and tenants not only for proactive maintenance, but
   also to ensure support of Service Level Agreements (SLAs).

   As the tunnel traverses different networks, OAM messages need to be
   translated at the edge of each network to ensure end-to-end OAM.

6. Summary

   The document describes some general potential use cases of NVO3 in
   DCs. The combination of these cases should give operators
   flexibility and capability to design more sophisticated cases for
   various purposes.

   DC services may vary from infrastructure as a service (IaaS),
   platform as a service (PaaS), to software as a service (SaaS), in
   which the network virtualization overlay is just a portion of an
   application service. NVO3 decouples the service
   construction/configurations from the DC network infrastructure
   configuration, and helps deployment of higher level services over
   the application.

   NVO3's underlying network provides the tunneling between NVEs so
   that two NVEs appear as one hop to each other. Many tunneling
   technologies can serve this function. The tunneling may in turn be
   tunneled over other intermediate tunnels over the Internet or other
   WANs. It is also possible that intra DC and inter DC tunnels are
   stitched together to form an end-to-end tunnel between two NVEs.

   A DC virtual network may be accessed via an external network in a
   secure way. Many existing technologies can help achieve this.

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   NVO3 implementation may vary. Some DC operators prefer to use
   centralized controller to manage tenant system reachbility in a
   tenant network, other prefer to use distributed protocols to
   advertise the tenant system location, i.e. attached NVEs. For the
   migration and special requirement, the different solutions may apply
   to one tenant network in a DC. When a tenant network spans across
   multiple DCs and WANs, each network administration domain may use
   different methods to distribute the tenant system locations. Both
   control plane and data plane interworking are necessary.

7. Security Considerations

   Security is a concern. DC operators need to provide a tenant a
   secured virtual network, which means one tenant's traffic isolated
   from the other tenant's traffic and non-tenant's traffic; they also
   need to prevent DC underlying network from any tenant application
   attacking through the tenant virtual network or one tenant
   application attacking another tenant application via DC networks.
   For example, a tenant application attempts to generate a large
   volume of traffic to overload DC underlying network. The NVO3
   solution has to address these issues.

8. IANA Considerations

   This document does not request any action from IANA.

9. Acknowledgements

   Authors like to thank Sue Hares, Young Lee, David Black, Pedro
   Marques, Mike McBride, David McDysan, Randy Bush, and Uma Chunduri
   for the review, comments, and suggestions.

10. References

10.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997

   [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
             Networks (VPNs)", RFC 4364, February 2006.

   [IEEE 802.1ag]  "Virtual Bridged Local Area Networks - Amendment 5:
             Connectivity Fault Management", December 2007.

   [ITU-T G.8013/Y.1731] OAM Functions and Mechanisms for Ethernet
             based Networks, 2011.

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   [ITU-T Y.1564] "Ethernet service activation test methodology", 2011.

   [RFC4378] Allan, D., Nadeau, T., "A Framework for Multi-Protocol
             Label Switching (MPLS) Operations and Management (OAM)",
             RFC4378, February 2006

   [RFC4301] Kent, S., "Security Architecture for the Internet
             Protocol", rfc4301, December 2005

   [RFC5880] Katz, D. and Ward, D., "Bidirectional Forwarding Detection
             (BFD)", rfc5880, June 2010.

10.2. Informative References

   [NVGRE]  Sridharan, M., "NVGRE: Network Virtualization using Generic
             Routing Encapsulation", draft-sridharan-virtualization-
             nvgre-02, work in progress.

   [NVO3PRBM] Narten, T., etc "Problem Statement: Overlays for Network
             Virtualization", draft-ietf-nvo3-overlay-problem-
             statement-02, work in progress.

   [NVO3FRWK] Lasserre, M., Motin, T., and etc, "Framework for DC
             Network Virtualization", draft-ietf-nvo3-framework-02,
             work in progress.

   [NVO3MCAST] Ghanwani, A., "Multicast Issues in Networks Using NVO3",
             draft-ghanwani-nvo3-mcast-issues-00, work in progress.

   [VRF-LITE] Cisco, "Configuring VRF-lite",

   [VXLAN]  Mahalingam,M., Dutt, D., etc "VXLAN: A Framework for
             Overlaying Virtualized Layer 2 Networks over Layer 3
             Networks", draft-mahalingam-dutt-dcops-vxlan-03.txt, work
             in progress.

 Authors' Addresses

   Lucy Yong
   Huawei Technologies,
   5340 Legacy Dr.
   Plano, TX 75025

   Phone: +1-469-277-5837

   Mehmet Toy

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   1800 Bishops Gate Blvd.,
   Mount Laurel, NJ 08054

   Phone : +1-856-792-2801
   E-mail :

   Aldrin Isaac

   Vishwas Manral
   Hewlett-Packard Corp.
   3000 Hanover Street, Building 20C
   Palo Alto, CA  95014

   Phone: 650-857-5501

   Linda Dunbar
   Huawei Technologies,
   5340 Legacy Dr.
   Plano, TX 75025 US

   Phone: +1-469-277-5840

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